the other hand, can intercept requests from the external network requesting a resource on a server internal to the network and filter it accordingly to reduce security threats. As these proxy servers are accessible to the external network, placing them in the DMZ can reinforce security.

DMZ Implementation

DMZ can be implemented in two different ways – using a single firewall and using a dual firewall.

DMZ Using A Single Firewall

A single firewall with three network interfaces can be used in this method. The first interface can be connected to the external network. The second interface can be connected to the DMZ, and the third interface can be connected to the internal network. In this case, as a single firewall is used, the firewall should be able to handle all traffic going to the DMZ and the traffic from the internal network and it can also become a single point of failure.

DMZ Using Dual Firewall

In this case, two different firewalls are used. The first firewall is placed between the external network and the DMZ. It can monitor all traffic between the external network and the DMZ and filter them accordingly. The second firewall can be placed between the DMZ and the internal network and monitor and filter traffic between the DMZ and the internal network. As two firewalls are used in this method, this is more secure than the single firewall method. Also, the two firewalls used should be from two different vendors so that both of them do not contain the same security vulnerabilities, and it becomes more difficult for the attackers to bypass both firewalls to access the internal network.

This was an introductory article on the DMZ. I hope it helps. Interested readers who want to know more about how different web application attacks work and how to prevent them may refer to the book Web Application Vulnerabilities And Prevention.